There's a bit of snobbery on this thread.
"If you're not an fx guy, I dare say you'd be fine with the standard. "
Erm, excuse me, I am an FX guy, a MASSIVE FX guy, probably more than you in fact. You can have tonnes of FX on a standard, just not with two cabs and amps.
The truth is the Standard is an FX junkies dream, sure the Ultra has some nice niche extras (vocoder? arpeggiator!?) and if you want the peace of mind of that extra CPU then fine, I understand that. But with the EXACT same tech and algorithms in the Standard how can anyone possibly say it's for non-FX people. Clearly people a little bit up themselves that's who.